This invention describes a method and apparatus for increasing the fuel efficiency and reducing the undesirable emissions of an internal combustion engine. While the general principles and teachings hereinafter disclosed are applicable to all combustion engines, the invention is hereinafter described in detail in connection with its application to a multi-cylinder, reciprocating, fuel injected, spark ignited, internal combustion engine.
As used herein, the term "conventional engine" refers to a device which converts heat energy, released by the combustion of a fuel, into mechanical energy in a rotating output shaft of the engine. Also, the term "valve control" is defined as controlling the intake and exhaust valves of a cylinder by varying their time of opening and closing or not opening at all, while driven by a conventional rotating camshaft. Also, the term "air compressor" is defined as using the engine to take energy from the inertial load driven by the engine to compress air in the engine cylinders and then store it in a reservoir. Also, the term "air motor" is defined as powering the engine by the controlled release of compressed air into the engine cylinders. Also the term "brake specific fuel consumption" (BSFC) is defined as the amount of fuel consumed to produce a given power at the engine drive shaft.
In the United States, the Federal law requires that passenger vehicles be tested over an urban driving cycle while the fuel consumed and exhaust emissions generated are measured. This driving cycle has many periods of acceleration, deceleration and idle, with few periods of steady state speed, and is intended to reflect typical urban usage. During deceleration and idle operation it is difficult to control emissions in typical automobile engines--particularly throttled engines--because of the low manifold pressures at these times. Also, when the accelerator is released, fuel continues to be consumed even though no energy is required from the engine. The emissions measured during this test must be less than those specified by law at the time of manufacture, and the fuel consumed is used in the determination of the manufacturer's Corporate Average Fuel Economy (CAFE) during that year.